What kinds of information should be kept in my workout journal? Should it just be a matrix of stats (exercise name, weight, reps, and date) or is there other important information that should be recorded on normal basis?

What should I record in my journal and what have others found to be useful journals while bouncing around a gym (paper, phone app, nothing and just record it later)?

Best is to write down what you did as soon as you finish it, else you'll forget. You might also want to write down how you felt during the exercise (eg. "last rep killed me", "breezed through it") and maybe even add some general notes after a workout ("hit the back good", "soreness in left elbow", "need more cardio" and such). That's pretty much all I ever wrote.
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VPericAug 16 '11 at 19:51

You don't write which type of exercises, you want tot record. That is very important, when deciding what type of information to store. E.g. for running and biking, you want to have your pace/speed, heart rate and route, whereas for weight-lifting these parameters will all be irrelevant.
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Tonny MadsenAug 17 '11 at 6:20

The idea is to set up your routine prior to the workout and track progress. My approach is a little simpler, I keep a small book, write down the exercises, check mark for each set and record the max weight.....I also put in how the workout was and how I felt. A journal could be used for many things, such as: tracking progress, sharing with a trainer, providing hints for changes, etc...but to me, the most important aspect is motivation - its good to see what progress you're making.

How you feel is very important, particularly when working with a coach. According to Practical Programming, severe overtraining can come with symptoms that look/feel like clinical depression--and mild overtraining can have reduced performance, symptoms of stress, etc.
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Berin LoritschAug 17 '11 at 13:54

The link I have provided may be used as a starting point for those interested in weight training.I have been training for a while and I find writing down my routine on paper really useful, motivating, convenient and less tedious than using apps or none. The pdf highlights the importance of training journal, tips on how to keep a good journal, advice on Build Muscle and Lose Fat, Gain Muscle While Staying Lean, Gain Weight and Size. For me if I have a journal with me at the gym I am more focused as opposed to being all over the place and doing the same thing.

You should record: date, time, what specific exercises you did, reps and sets, what body parts you focused on, duration of workout, intensity of workout, your mood, your energy levels, how you felt during the workout, your eating plans, your goals for the next workout, your weight, heart rate and anything else you can think of! The more detail the better because it provides you with more of a complex picture when reviewing your past workouts and progress!

The single most important stat you should record is your pulse when you wake up. The lower it is, the better your condition is.

Even if you can do more reps and lift more weight, but your heartbeat stays the same, it means your doing something very wrong - the single the most important muscle, heart, is not following your arms, legs, abdomen or whatever you are doing.

Meade Rubenstein's and timanzo's answers are great but what they didn't mention and I think is important is the tempo you push/pull weights. For a faster muscle growth it's recommended to vary your tempo every (two) week(s), so one week you push/pull the weight very slow and the other you push/pull it fast. Writing it down gives you an overview of how you vary your training and sometimes your able to push/pull more weight when doing the excersice fast or slow that's why you should also add this information.